The present invention provides a detergent tablet comprising a compressed portion and a non-compressed, non-encapsulating portion.
Detergent compositions in tablet form are known in the art. It is understood that detergent compositions in tablet form hold several advantages over detergent compositions in particulate form, such as ease of handling, transportation and storage.
Detergent tablets are most commonly prepared by pre-mixing components of a detergent composition and forming the pre-mixed detergent components into a tablet using a tablet press. Tablets are typically formed by compression of the components of the detergent composition into a tablet. However, the Applicant has found that some components of a detergent composition are adversely affected by the compression pressure used to form the tablets. These components could not previously be included in a detergent tablet composition without sustaining a loss in performance. In some cases the components may even have become unstable or inactive as a result of the compression.
Furthermore as the components of the detergent composition are compressed, the components are brought into close proximity with each other. A result of the close proximity of the components can be that certain of the components react with each other, becoming unstable, inactive or exhausted. A solution to this problem, as seen in the prior art, has been to separate components of the detergent composition that may potentially react with each other when the detergent composition is compressed into tablet form. Separation of the components has been achieved by, for example, preparing multiple-layer tablets wherein the components that may potentially react with each other are contained in different layers of the tablet. Multiple-layer tablets, are traditionally prepared using multiple compression steps. Layers of the tablet that are subjected to more than one compression step are subjected to a cumulative and potentially greater overall compression pressure. An increase in compression pressure of the tabletting press is known to decrease the rate of dissolution of the tablet with the effect that such multiple layer may not dissolve satisfactorily in use.
Other methods of achieving separation of detergent components have been described. For example EP-A 0,224,135 describes a dishwashing detergent in a form which comprises a warm water-soluble melt, into which is pressed a cold water-soluble tablet. The document teaches a detergent composition that consists of two parts, the first part dissolving in the pre-rinse and the second part dissolving in the main wash of the dishwasher.
EP-B-0,055,100 describes a lavatory block formed by combining a slow dissolving shaped body with a tablet. The lavatory block is designed to be placed in the cistern of a lavatory and dissolves over a period of days, preferably weeks. As a means of controlling the dissolution of the lavatory block, the document teaches admixing one or more solubility control agents. Examples of such solubility control agents are paradichlorobenzene, waxes, long chain fatty acids and alcohols and esters thereof and fatty alkylamides. Detergent tablets for use in laundry or automatic dishwashing must substantially dissolve within one cycle of the washing or dishwashing machine, i.e. within 30 to 120 minutes.
The Applicant has found that by providing a detergent tablet comprising a compressed portion and a non-encapsulating, non-compressed portion detergent components previously considered to be unacceptable for detergent tablets, can be incorporated into a detergent tablet. In addition, potentially reactive components of the detergent composition can be effectively separated.
A further advantage of using a detergent tablet as described herein, is the performance benefits which may be achieved in being able to prepare the detergent tablet so that if required, the compressed portion and the non-compressed portion have different rates of dissolution. Such performance benefits are achieved by selectively delivering active detergent components into the wash solution at different times.
According to the present invention there is provided a detergent tablet comprising:
(a) a compressed portion comprising an active detergent component; and
(b) a non-compressed, non-encapsulating portion comprising an active detergent component, wherein the detergent tablet comprises an enzyme.
In an alternative embodiment there is also provided a detergent tablet comprising:
(a) a compressed portion comprising an active detergent component; and
(b) a non-compressed, non-encapsulating portion comprising an active detergent component, wherein the weight ratio of compressed to non-compressed portion is greater than 0.5:1 and the detergent tablet comprises silicate.
In another alternative embodiment there is provided a detergent tablet comprising:
(a) a compressed portion comprising an active detergent component; and
(b) a non-compressed, non-encapsulating portion comprising an active detergent component, wherein the weight ratio of compressed to non-compressed portion is greater than 0.5:1 and the detergent tablet has a dissolution rate of greater than 0.33 g/min as determined using the SOTAX dissolution test method described herein.
In yet another alternative embodiment there is provided a detergent tablet comprising:
(a) a compressed portion comprising an active detergent component; and
(b) a non-compressed, non-encapsulating portion comprising an active detergent component, wherein the weight of the detergent tablet is less than 40 g and the detergent tablet has a dissolution rate of greater than 0.33 g/min as determined using the SOTAX dissolution test method described herein.
In yet another alternative embodiment there is provided a detergent tablet comprising:
(a) a compressed portion comprising an active detergent component; and
(b) a non-compressed, non-encapsulating portion comprising an active detergent component wherein the compressed portion provides a mould to accommodate the non-compressed portion.
In addition there is also provided a process for preparing the detergent tablets described herein.
Thus, in accordance with the present invention it has been found that active detergent components of a detergent tablet previously adversely affected by the compression pressure used to form the tablets can now be included in a detergent tablet. Examples of these components include bleaching agents and enzymes. In addition, in accordance with the present invention, it has been found that active detergent components of a detergent tablet may be separated from one another by having one or more compatible components contained in a compressed portion and one or more compatible components contained in a non-compressed portion of the tablet. Examples of components that may interact and may therefore require separation include bleaching agents, bleach activators or catalyst and enzymes; bleaching agents and bleach catalysts or activators; bleaching agents and surfactants; alkalinity sources and enzymes.
Furthermore, it may be advantageous to provide the compressed and the non-compressed portions such that they dissolve in wash water with different dissolution rates. By controlling the rate of dissolution of each portion relative to one another, and by selection of the active detergent components in the respective portions, their order of release into the wash water can be controlled and the cleaning performance of the detergent tablet may be improved. For example it is often preferred that enzymes are delivered to the wash prior to bleaching agent and/or bleach activator. It may also be preferred that a source of alkalinity is released into the wash water more rapidly than other components of the detergent tablet. It is also envisaged that it may be advantageous to prepare a detergent tablet according to the present invention wherein the release of certain components of the tablet is delayed relative to other components.
It is also envisaged that the tablet may comprise a plurality of compressed or non-compressed portions. For example, a plurality of compressed portions may be arranged in layers and/or a plurality of non-compressed portions may be present as discrete sections of the tablet separated by a compressed portion. Thus, there may be a first and a second and optional subsequent compressed and/or non-compressed portions, each comprising an active detergent component and where at least the first and second portions may comprise different active detergent components or mixtures of components. Such a plurality of compressed or non-compressed portions may be advantageous, enabling a tablet to be produced which has for example, a first and second and optional subsequent portions so that they have different rates of dissolution. Such performance benefits are achieved by selectively delivering active detergent components into the wash water at different times.
The detergent tablets described herein are preferably between 15 g and 100 g in weight, more preferably between 18 g and 80 g in weight, even more preferably between 20 g and 60 g in weight. The detergent tablet described herein that are suitable for use in automatic dishwashing methods are most preferably between 20 g and 40 g in weight Detergent tablets suitable for use in fabric laundering methods are most preferably between 40 g and 100 g, more preferably between 40 g and 80 g, most preferably between 40 g and 65 g in weight. The weight ratio of compressed portion to non-compressed portion is generally greater than 0.5:1, preferably greater than 1:1, more preferably greater than 2:1, even more preferably greater than 3:1 or even 4:1, most preferably at least 5:1.
The detergent tablets described herein have Child Bite Strength (CBS) which is generally greater than 10 Kg, preferably greater than 12 Kg, most preferably greater than 14 Kg. CBS is measured as per the U.S. Consumer Product Safety Commission Test Specification.
Child Bite Strength Test Method: According to this method the tablet is placed horizontally between two strips/plates of metal. The upper and lower plates are hinged on one side, such that the plates resemble a human jaw. An increasing downward force is applied to the upper plate, mimicking the closing action of the jaw, until the tablet breaks. The CBS of the tablet is a measure of the force in Kilograms, required to break the tablet.
The detergent tablets described herein generally have a dissolution rate of faster than 0.33 g/min, preferably faster than 0.5 g/min, more preferably faster than 1.00 g/min, even more preferably faster than 2.00 g/m, most preferably faster than 2.73 g/min. Dissolution rate is measured using the SOTAX dissolution test method. For the purposes of the present invention dissolution of detergent tablets is achieved using a SOTAX (tradename) machine; model number AT7 available from SOTAX.
SOTAX Dissolution Test Method: The SOTAX machine consists of a temperature controlled waterbath with lid. 7 pots are suspended in the water bath. 7 electric stirring rods are suspended from the underside of the lid, in positions corresponding to the position of the pots in the waterbath. The lid of the waterbath also serves as a lid on the pots.
The SOTAX waterbath is filled with water and the temperature gauge set to 50xc2x0 C. Each pot is then filled with 1 litre of deionised water and the stirrer set to revolve at 250 rpm. The lid of the waterbath is closed, allowing the temperature of the deionised water in the pots to equilibrate with the water in the waterbath for 1 hour.
The tablets are weighed and one tablet is placed in each pot, the lid is then closed. The tablet is visually monitored until it completely dissolves. The time is noted when the tablet has completely dissolved. The dissolution rate of the tablet is calculated as the average weight (g) of tablet dissolved in deionised water per minute.
The compressed portion of the detergent tablet comprises at least one active detergent component but may comprise a mixture of more than one active detergent components, which are compressed. Any detergent tablet component conventionally used in known detergent tablets is suitable for incorporation into the compressed portion of the detergent tablets of this invention. Suitable active detergent components are described hereinafter. Preferred active detergent components include builder compound, surfactant, bleaching agent, bleach activator, bleach catalyst, enzyme and an alkalinity source.
Active detergent component(s) present in the compressed layer may optionally be prepared in combination with a carrier and/or a binder for example water, polymer (e.g. PEG), liquid silicate. The active detergent components are preferably prepared in particulate form (i.e. powder or granular form) and may be prepared by any known method, for example conventional spray drying, granulation or agglomeration. The particulate active detergent component(s) are then compressed using any suitable equipment suitable for forming compressed tablets, blocks, bricks or briquettes; described in more detail hereafter.
The non-compressed, non-encapsulating portion (hereinafter non-compressed portion) comprises at least one active detergent component, but may comprise a mixture of more than one active detergent components. Active detergent components suitable for incorporation in the non-compressed portion include components that interact with one or more detergent components present in the compressed portion. In particular, preferred components of the non-compressed portion are those that are adversely affected by compression pressure of for example a compression tablet press. Examples of such active detergent components include, but are not limited to, surfactant, bleaching agent, bleach activator, bleach catalyst, enzyme, corrosion inhibitor, perfume and an alkalinity source. These components are described in more detail below. The active detergent component(s) may be in any form for example particulate (i.e. powder or granular), gel or liquid form. The non-compressed portion in addition to comprising an active detergent component, may also optionally comprise a carrier component. The active detergent component may be present in the form of a solid, gel or liquid, prior to combination with a carrier component.
The non-compressed portion of the detergent tablet may be in solid, gel or liquid form.
The detergent tablet of the present invention requires that the non-compressed portion be delivered to the compressed portion such that the compressed portion and non-compressed portion contact each other. The non-compressed portion may be delivered to the compressed portion in solid or flowable form. Where the non-compressed portion is in solid form, it is pre-prepared, optionally shaped and then delivered to the compressed portion. The non-compressed portion is then affixed to a pre-formed compressed portion, for example by adhesion or by insertion of the non-compressed portion to a co-operating surface of the compressed portion.
Preferably the compressed portion comprises a pre-prepared depression or mould into which the non-compressed portion is delivered.
The non-compressed portion is preferably delivered to the compressed portion in flowable form. The non-compressed portion is then affixed to the compressed portion for example by adhesion, by forming a coating over the non-compressed layer to secure it to the compressed portion, or by hardening, for example (i) by cooling to below the melting point where the flowable composition becomes a solidified melt; (ii) by evaporation of a solvent; (iii) by crystallisation; (iv) by polymerisation of a polymeric component of the flowable non-compressed portion; (v) through pseudo-plastic properties where the flowable non-compressed portion comprises a polymer and shear forces are applied to the non-compressed portion; (vi) combining a binding agent with the flowable non-compressed portion. In an alternative embodiment the flowable non-compressed portion may be an extrudate that is affixed to the compressed portion by for example any of the mechanism described above or by expansion of the extrudate to the parameters of a mould provided by the compressed portion.
Preferably the compressed portion comprises a pre-prepared depression or mould (hereafter referred to as xe2x80x98mouldxe2x80x99) into which the non-compressed portion is delivered. In an alternative embodiment the surface of the compressed portion comprises more than one mould into which the non-compressed portion may be delivered. The mould(s) preferably at least partially accommodates one or more non-compressed portions. The non-compressed portion(s) is then delivered into the mould and affixed to the compressed portion as described above.
The non-compressed portion may comprise particulates. The particulates may be prepared by any known method, for example conventional spray drying, granulation, encapsulation or agglomeration. Particulates may be affixed to the compressed portion by incorporating a binding agent or by forming a coating layer over the non-compressed portion.
Where the detergent tablet comprises more than one non-compressed portion, the first and second and optional subsequent non-compressed portions may comprise particulates having substantially different average particle size. By substantially different average particle size we mean that the difference between the average particle size of the first and second and/or subsequent compositions is greater than 5%, preferably greater than 10%, more preferably greater than 15% or even 20% of the smaller average particle size.
The average particle size of the particulate detergent active components used herein is calculated using a series of Tyler sieves. The series consists of a number of sieves each having a different aperture size. Samples of a composition of active detergent components are sieved through the series of sieves (typically 5 sieves). The weight of a sample of composition retained in the sieve is plotted against the aperture size of the sieve. The average particle size of the composition is defined as the aperture size through which 50% by weight of the sample of composition would pass.
In another embodiment the first and second and optional subsequent compositions of active detergent components have substantially different density such that the difference between the density of the first and second and/or subsequent compositions is greater than 5%, preferably greater than 10%, more preferably greater than 15% or even 20% of the smaller density. Density of the particulate composition of active detergent components can be measured by any known method suitable for measuring density of particulate material.
Preferably the density of the composition of active detergent components is measured using a simple ftmnnel and cup device consisting of a conical funnel moulded rigidly on a base and provided with a flap valve at its lower extremity to allow the contents of the fimnel to be emptied into an axially aligned cylindrical cup disposed below the finnel. The fnnnel is 130 mm high and has internal diameters of 130 mm and 40 mm at its respective upper and lower extremities. It is mounted so that the lower extremity is 140 mm above the upper surface of the base. The cup has an overall height of 90 mm, an internal height of 87 mm and an internal diameter of 84 mm. Its nominal volume is 500 ml.
A density measurement is taken by hand pouring the composition into the funnel. Once the funnel is filled, the flap valve is opened and powder allowed to run through the funnel, overfilling the cup. The filled cup is removed from the frame and excess powder removed from the cup by passing a straight edged implement e.g. a knife, across its upper edge. The filled cup is then weighed and the value obtained for the weight of powder doubled to provide a bulk density in grams/litre. Replicate measurements are made as required.
Tablets in which one or more of the non-compressed portions comprise particulates and the average particle size and/or density of the first and second and optionally subsequent non-compressed portions are substantially different are preferred where the first and second and optionally subsequent non-compressed portions are required to have different rates of dissolution.
Where the non-compressed portion comprises a solidified melt, the melt is prepared by heating a composition comprising a detergent active component and optional carrier component(s) to above its melting point to form a flowable melt. The flowable melt is then poured into a mould and allowed to cool. As the melt cools it becomes solid, taking the shape of the mould at ambient temperature. Where the composition comprises one or more carrier components, the carrier component(s) may be heated to above their melting point, and then an active detergent component may be added. Carrier components suitable for preparing a solidified melt are typically non-active components that can be heated to above melting point to form a liquid and cooled to form an intermolecular matrix that can effectively trap active detergent components. A preferred non-active carrier component is an organic polymer that is solid at ambient temperature. Preferably the non-active detergent components is polyethylene glycol (PEG). The compressed portion of the detergent tablet preferably provides a mould to accommodate the melt.
The flowable non-compressed portion may be in a form comprising a dissolved or suspended active detergent component. The flowable non-compressed portion may harden over time to form a solid, semi solid or highly viscous liquid non-compressed portion by any of the methods described above. In particular, the flowable non-compressed portion may harden by evaporation of a solvent. Solvents suitable for use herein may include any known solvent in which a binding agent is soluble. Preferred solvents may be polar or non-polar and may include water, alcohol, (for example ethanol, acetone) and alcohol derivatives. In an alternative embodiment more than one solvent may be used.
The flowable non-compressed portion may comprise one or more binding agents. Any binding agent that has the effect of causing the composition to become solid, semi-solid or highly viscous over time is envisaged for use herein. Although not wishing to be bound by theory, it is believed that mechanisms by which the binding agent causes a non-solid composition to become solid, semi-solid or highly viscous include: chemical reaction (such as chemical cross linking), or effect interaction between two or more components of the flowable compositions either; chemical or physical interaction of the binding agent with a component of the composition. Preferred binding agents include a sugar/gelatine combination, starch, glycerol and organic polymers. The sugar may be any monosaccharide (e.g. glucose), disaccharide (e.g. sucrose or maltose) or polysaccharide. The most preferred sugar is commonly available sucrose. For the purposes of the present invention type A or B gelatine may be used, available from for example Sigma. Type A gelatine is preferred since it has greater stability in alkaline conditions in comparison to type B. Preferred gelatine also has a bloom strength of between 65 and 300, most preferably between 75 and 100. Preferred organic polymers include polyethylene glycol (PEG) of molecular weight from 500 to 10,000, preferably from 750 to 8000, most preferably from 1000 to 6000 available from Hoechst.
Where the non-compressed portion is an extrudate, the extrudate is prepared by premixing the active detergent components with optional carrier components to form a viscous paste. The viscous paste is then extruded using any suitable commonly available extrusion equipment such as for example a single or twin screw extruder available from for example APV Baker, Peterborough, U.K. The extrudate is then cut to size either after delivery to the compressed portion, or prior to delivery to the compressed portion of the detergent tablet. The compressed portion of the tablet preferably comprises a mould into which the extruded non-compressed portion may be delivered.
In a preferred embodiment the non-compressed portion is coated with a coating layer. The coating may be used to affix a non-compressed portion to the compressed portion. This may be particularly advantageous where the non-compressed portion comprises flowable particulates, gels or liquids.
The coating layer preferably comprises a material that becomes solid on contacting the compressed and/or the non-compressed portions within preferably less than 15 minutes, more preferably less than 10 minutes, even more preferably less than 5 minutes, most preferably less than 60 seconds. Preferably the coating layer is water-soluble. Preferred coating layers comprise materials selected from the group consisting of fatty acids, alcohols, diols, esters and ethers, adipic acid, carboxylic acid, dicarboxylic acid, polyvinyl acetate (PVA), polyvinyl pyrrolidone (PVP), polyacetic acid (PLA), polyethylene glycol (PEG) and mixtures thereof. Preferred carboxylic or dicarboxylic acids preferably comprise an even number of carbon atoms. Preferably carboxylic or dicarboxylic acids comprise at least 4, more preferably at least 6, even more preferably at least 8 carbon atoms, most preferably between 8 and 13 carbon atoms. Preferred dicarboxylic acids include adipic acid, suberic acid, azelaic acid, subacic acid, undecanedioic acid, dodecandioic acid, tridecanedioic and mixtures thereof. Preferred fatty acids are those having a carbon chain length of from C12 to C22, most preferably from C18 to C22. The coating layer may also preferably comprise a disrupting agent. Where present the coating layer generally present at a level of at least 0.05%, preferably at least 0. 1%, more preferably at least 1%, most preferably at least 2% or even at least 5% of the detergent tablet.
As an alternative embodiment the coating layer may encapsulate the detergent tablet. In this embodiment the coating layer is present at a level of at least 4%, more preferably at least 5%, most preferably at least 10% of the detergent tablet.
In a preferred embodiment the compressed and/or non-compressed portions and/or coating layer additionally comprise a disrupting agent. The disrupting agent may be a disintegrating or effervescing agent. Suitable disintegrating agents include agents that swell on contact with water or facilitated water influx and/or efflux by forming channels in compressed and/or non-compressed portions. Any known disintegrating or effervescing agent suitable for use in laundry or dishwashing applications is envisaged for use herein. Suitable disintegrating agent include starch, starch derivatives, alginates, carboxymethylcellulose (CMC), CMC-based polymers, sodium acetate, aluminium oxide. Suitable effervescing agents are those that produce a gas on contact with water. Suitable effervesing agents may be oxygen, nitrogen dioxide or carbon dioxide evolving species. Examples of preferred effervesing agents may be selected from the group consisting of perborate, percarbonate, carbonate, bicarbonate and carboxylic acids such as citric or maleic acid.
An advantage of including a disrupting agent in the detergent tablet of the present invention is the transport, storage and handling benefits that can be achieved by increasing the hardness of the detergent tablet without adversely affecting the cleaning performance.
According to the present invention there is also provided a process for preparing a detergent tablet comprising the steps of:
a) compressing an active detergent component to form a compressed portion; and
b) delivering a non-compressed, non-encapsulating portion comprising an active detergent component to the compressed portion.
As described above, the detergent tablets described herein are prepared by separately preparing the composition of active detergent components forming the respective compressed portion and the non-compressed portion, then delivering or adhering the composition of the non-compressed portion to the compressed portion.
The compressed portion is prepared by obtaining at least one active detergent component and optionally premixing with carrier components. Any pre-mixing will be carried out in a suitable mixer; for example a pan mixer, rotary drum, vertical blender or high shear mixer. Preferably dry particulate components are admixed in a mixer, as described above, and liquid components are applied to the dry particulate components, for example by spraying the liquid components directly onto the dry particulate components. The resulting composition is then formed into a compressed portion in a compression step using any known suitable equipment. Preferably the composition is formed into a compressed portion using a tablet press, wherein the tablet is prepared by compression of the composition between an upper and a lower punch. In a preferred embodiment of the present invention the composition is delivered into a punch cavity of a tablet press and compressed to form a compressed portion using a pressure of preferably greater than 6.3 KN/cm2 more preferably greater than 9 KN/cm2, most preferably greater than 14.4 KN/cm2.
In order to form a preferred tablet of the invention, wherein the compressed portion provides a mould to receive the non-compressed portion, the compressed portion is prepared using a modified tablet press comprising modified upper and/or lower punches. The upper and lower punches of the modified tablet press are modified such that the compressed portion provides one or more indentations which form a mould(s) to which the non-compressed portion is delivered.
The non-compressed portion comprises at least one active detergent component. Where the non-compressed portion comprises more than one active detergent component the components are pre-mixed using any known suitable mixing equipment. In addition the non-compressed portion may optionally comprise a carrier with which the active detergent components are combined. The non-compressed portion may be prepared in solid or flowable form. Once prepared the composition is delivered to the compressed portion. The non-compressed portion may be delivered to the compressed portion by manual delivery or using a nozzle feeder or extruder. Where the compressed portion comprises a mould, the non-compressed portion is preferably delivered to the mould using accurate delivery equipment, for example a nozzle feeder, such as a loss in weight screw feeder available from Optima, Germany or an extruder.
Where the flowable non-compressed portion is in particulate form the process comprises delivering a flowable non-compressed portion to the compressed portion in a delivery step and then coating at least a portion of the non-compressed portion with a coating layer such that the coating layer has the effect of substantially adhering the non-compressed portion to the compressed portion.
Where the flowable non-compressed portion is affixed to the compressed portion by hardening, the process comprises a delivery step in which the flowable non-compressed portion is delivered to the compressed portion and a subsequent conditioning step, wherein the non-compressed portion hardens. Such a conditioning step may comprise drying, cooling, binding, polymerisation etc. of the non-compressed portion, during which the non-compressed portion becomes solid, semi-solid or highly viscous. Heat may be used in a drying step. Heat, or exposure to radiation may be used to effect polymerisation in a polymerisation step.
It is also envisaged that the compressed portion may be prepared having a plurality of moulds. The plurality of moulds are then filled with a non-compressed portion. It is also envisaged that each mould can be filled with a different non-compressed portion or alternatively, each mould can be filled with a plurality of different non-compressed portions.
The compressed portion of the detergent tablets described herein are prepared by compression composition of active detergent components. A suitable composition may include a variety of different detergent active components including builder compounds, surfactants, enzymes, bleaching agents, alkalinity sources, colourants, perfime, lime soap dispersants, organic polymeric compounds including polymeric dye transfer inhibiting agents, crystal growth inhibitors, heavy metal ion sequestrants, metal ion salts, enzyme stabilisers, corrosion inhibitors, suds suppressers, solvents, fabric softening agents, optical brighteners and hydrotropes.
Highly preferred active detergent components include a builder compound, a surfactant, an enzyme and a bleaching agent.
The detergent tablets of the present invention preferably contain a builder compound, typically present at a level of from 1% to 80% by weight, preferably from 10% to 70% by weight, most preferably from 20% to 60% by weight of the composition of active detergent components.
Suitable water-soluble builder compounds include the water soluble monomeric polycarboxylates, or their acid forms, homo or copolymeric polycarboxylic acids or their salts in which the polycarboxylic acid comprises at least two carboxylic radicals separated from each other by not more that two carbon atoms, carbonates, bicarbonates, borates, phosphates, and mixtures of any of the foregoing.
The carboxylate or polycarboxylate builder can be monomeric or oligomeric in type although monomeric polycarboxylates are generally preferred for reasons of cost and performance.
Suitable carboxylates containing one carboxy group include the water soluble salts of lactic acid, glycolic acid and ether derivatives thereof. Polycarboxylates containing two carboxy groups include the water-soluble salts of succinic acid, malonic acid, (ethylenedioxy) diacetic acid, maleic acid, diglycolic acid, tartaric acid, tartronic acid and flumaric acid, as well as the ether carboxylates and the sulfinyl carboxylates. Polycarboxylates containing three carboxy groups include, in particular, water-soluble citrates, aconitrates and citraconates as well as succinate derivatives such as the carboxymethyloxysuccinates described in British Patent No. 1,379,241, lactoxysuccinates described in British Patent No. 1,389,732, and aminosuccinates described in Netherlands Application 7205873, and the oxypolycarboxylate materials such as 2-oxa-1,1,3-propane tricarboxylates described in British Patent No. 1,387,447.
Polycarboxylates containing four carboxy groups include oxydisuccinates disclosed in British Patent No. 1,261,829, 1,1,2,2-ethane tetracarboxylates, 1,1,3,3-propane tetracarboxylates and 1,1,2,3-propane tetracarboxylates. Polycarboxylates containing sulfo substituents include the sulfosuccinate derivatives disclosed in British Patent Nos. 1,398,421 and 1,398,422 and in U.S. Pat. No. 3,936,448, and the sulfonated pyrolysed citrates described in British Patent No. 1,439,000.
Alicyclic and heterocyclic polycarboxylates include cyclopentane-cis,cis, cis-tetracarboxylates, cyclopentadienide pentacarboxylates, 2,3,4,5-tetrahydrofuran-cis, cis, cis-tetracarboxylates, 2,5-tetrahydrofuran-cis-dicarboxylates, 2,2,5,5-tetrahydrofuran-tetracarboxylates, 1,2,3,4,5,6-hexane-hexacarboxylates and carboxymethyl derivatives of polyhydric alcohols such as sorbitol, mannitol and xylitol. Aromatic polycarboxylates include mellitic acid, pyromellitic acid and the phthalic acid derivatives disclosed in British Patent No. 1,425,343.
Of the above, the preferred polycarboxylates are hydroxycarboxylates containing up to three carboxy groups per molecule, more particularly citrates.
The parent acids of the monomeric or oligomeric polycarboxylate chelating agents or mixtures thereof with their salts, e.g. citric acid or citrate/citric acid mixtures are also contemplated as usefuil builder components.
Borate builders, as well as builders containing borate-forming materials that can produce borate under detergent storage or wash conditions can also be used but are not preferred at wash conditions less that 50xc2x0 C., especially less than 40xc2x0 C.
Examples of carbonate builders are the alkaline earth and alkali metal carbonates, including sodium carbonate and sesqui-carbonate and mixtures thereof with ultra-fine calcium carbonate as disclosed in German Patent Application No. 2,321,001 published on Nov. 15, 1973.
Highly preferred builder compounds for use in the present invention are water-soluble phosphate builders. Specific examples of water-soluble phosphate builders are the alkali metal tripolyphosphates, sodium, potassium and ammonium pyrophosphate, sodium and potassium and ammonium pyrdphosphate, sodium and potassium orthophosphate, sodium polymeta/phosphate in which the degree of polymerisation ranges from 6 to 21, and salts of phytic acid.
Specific examples of water-soluble phosphate builders are the alkali metal tripolyphosphates, sodium, potassium and ammonium pyrophosphate, sodium and potassium and ammonium pyrophosphate, sodium and potassium orthophosphate, sodium polymeta/phosphate in which the degree of polymerization ranges from 6 to 21, and salts of phytic acid.
The detergent tablets of the present invention may contain a partially soluble or insoluble builder compound. Partially soluble and insoluble builder compounds are particularly suitable for use in tablets prepared for use in laundry cleaning methods. Examples of partially water soluble builders include the crystalline layered silicates as disclosed for example, in EP-A-0164514, DE-A-3417649 and DE-A-3742043. Preferred are the crystalline layered sodium silicates of general formula
NaMSixO2+1.yH2O
wherein M is sodium or hydrogen, x is a number from 1.9 to 4 and y is a number from 0 to 20. Crystalline layered sodium silicates of this type preferably have a two dimensional xe2x80x98sheetxe2x80x99 structure, such as the so called xcex4-layered structure, as described in EP 0 164514 and EP 0 293640.
Methods for preparation of crystalline layered silicates of this type are disclosed in DE-A-3417649 and DE-A-3742043. For the purpose of the present invention, x in the general formula above has a value of 2,3 or 4 and is preferably 2.
The most preferred crystalline layered sodium silicate compound has the formula xcex4-Na2Si2O5, known as NaSKS-6 (trade name), available from Hoechst AG.
The crystalline layered sodium silicate material is preferably present in granular detergent compositions as a particulate in intimate admixture with a solid, water-soluble ionisable material as described in PCT Patent Application No. WO 92/18594. The solid, water-soluble ionisable material is selected from organic acids, organic and inorganic acid salts and mixtures thereof, with citric acid being preferred.
Examples of largely water insoluble builders include the sodium aluminosilicates. Suitable aluminosilicates include the aluminosilicate zeolites having the unit cell formula Naz[(AlO2)z(SiO2)y]. xH2O wherein z and y are at least 6; the molar ratio of z to y is from 1.0 to 0.5 and x is at least 5, preferably from 7.5 to 276, more preferably from 10 to 264. The aluminosilicate material are in hydrated form and are preferably crystalline, containing from 10% to 28%, more preferably from 18% to 22% water in bound form.
The aluninosilicate zeolites can be naturally occurring materials, but are preferably synthetically derived. Synthetic crystalline aluminosilicate ion exchange materials are available under the designations Zeolite A, Zeolite B, Zeolite P, Zeolite X, Zeolite HS and mixtures thereof.
A preferred method of synthesizing aluminosilicate zeolites is that described by Schoeman et al (published in Zeolite (1994) 14(2), 110-116), in which the author describes a method of preparing colloidal aluminosilicate zeolites. The colloidal aluminosilicate zeolite particles should preferably be such that no more than 5% of the particles are of size greater than 1 xcexcm in diameter and not more than 5% of particles are of size less then 0.05 xcexcm in diameter. Preferably the aluminosilicate zeolite particles have an average particle size diameter of between 0.01 xcexcm and 1 xcexcm, more preferably between 0.05 xcexcm and 0.9 xcexcm, most preferably between 0.1 xcexcm and 0.6 xcexcm.
Zeolite A has the formula
Na12[AlO2)12(SiO2)12].xH2O
wherein x is from 20 to 30, especially 27. Zeolite X has the formula Na86 [(AlO2)86(SiO2)106]. 276 H2O. Zeolite MAP, as disclosed in EP-B-384,070 is a preferred zeolite builder herein.
Preferred aluminosilicate zeolites are the colloidal aluminosilicate zeolites. When employed as a component of a detergent composition colloidal aluminosilicate zeolites, especially colloidal zeolite A, provide enhanced builder performance in terms of providing improved stain removal. Enhanced builder performance is also seen in terms of reduced fabric encrustation and improved fabric whiteness maintenance; problems believed to be associated with poorly built detergent compositions.
A surprising finding is that mixed aluminosilicate zeolite detergent compositions comprising colloidal zeolite A and colloidal zeolite Y provide equal calcium ion sequestration performance versus an equal weight of commercially available zeolite A. Another surprising finding is that mixed aluminosilicate zeolite detergent compositions, described above, provide improved magnesium ion sequestration performance versus an equal weight of commercially available zeolite A.
Surfactants are preferred detergent active components of the compositions described herein. Suitable surfactants are selected from anionic, cationic, nonionic ampholytic and zwitterionic surfactants and mixtures thereof Automatic dishwashing machine products should be low foaming in character and thus the foaming of the surfactant system for use in dishwashing methods must be suppressed or more preferably be low foaming, typically nonionic in character. Sudsing caused by surfactant systems used in laundry cleaning methods need not be suppressed to the same extent as is necessary for dishwashing. The surfactant is typically present at a level of from 0.2% to 30% by weight, more preferably from 0.5% to 10% by weight, most preferably from 1% to 5% by weight of the composition of active detergent components.
A typical listing of anionic, nonionic, ampholytic and zwitterionic classes, and species of these surfactants, is given in U.S. Pat. No. 3,929,678 issued to Laughlin and Heuring on Dec. 30, 1975. A list of suitable cationic surfactants is given in U.S. Pat. No. 4,259,217 issued to Murphy on Mar. 31, 1981. A listing of surfactants typically included in automatic dishwashing detergent compositions is given for example, in EP-A-0414 549 and PCT Applications Nos. WO 93/08876 and WO 93/08874.
Essentially any nonionic surfactants useful for detersive purposes can be included in the detergent tablet. Preferred, non-limiting classes of usefuil nonionic surfactants are listed below.
The alkyl ethoxylate condensation products of aliphatic alcohols with from 1 to 25 moles of ethylene oxide are suitable for use herein. The alkyl chain of the aliphatic alcohol can either be straight or branched, primary or secondary, and generally contains from 6 to 22 carbon atoms. Particularly preferred are the condensation products of alcohols having an alkyl group containing from 8 to 20 carbon atoms with from 2 to 10 moles of ethylene oxide per mole of alcohol.
A suitable endcapped alkyl alkoxylate surfactant is the epoxy-capped poly(oxyalkylated) alcohols represented by the formula:
xe2x80x83R1O[CH2CH(CH3)O]x[CH2CH2O]y[CH2CH(OH)R2]xe2x80x83xe2x80x83(I)
wherein R1 is a linear or branched, aliphatic hydrocarbon radical having from 4 to 18 carbon atoms; R2 is a linear or branched aliphatic hydrocarbon radical having from 2 to 26 carbon atoms; x is an integer having an average value of from 0.5 to 1.5, more preferably 1; and y is an integer having a value of at least 15, more preferably at least 20.
Preferably, the surfactant of formula I, at least 10 carbon atoms in the terminal epoxide unit [CH2CH(OH)R2]. Suitable surfactants of formula I, according to the present invention, are Olin Corporation""s POLY-TERGENTO(copyright) SLF-18B nonionic surfactants, as described, for example, in WO 94/22800, published Oct. 13, 1994 by Olin Corporation.
Preferred surfactants for use herein include ether-capped poly(oxyalkylated)alcohols having the formula:
R1O[CH2CH(R3)O]x[CH2]kCH(OH)[CH2]jOR2
wherein R1 and R2 are linear or branched, saturated or unsaturated, aliphatic or aromatic hydrocarbon radicals having from 1 to 30 carbon atoms; R3 is H, or a linear aliphatic hydrocarbon radical having from 1 to 4 carbon atoms; x is an integer having an average value from 1 to 30, wherein when x is 2 or greater R3 may be the same or different and k and j are integers having an average value of from 1 to 12, and more preferably 1 to 5.
R1 and R2 are preferably linear or branched, saturated or unsaturated, aliphatic or aromatic hydrocarbon radicals having from 6 to 22 carbon atoms with 8 to 18 carbon atoms being most preferred. H or a linear aliphatic hydrocarbon radical having from 1 to 2 carbon atoms is most preferred for R3. Preferably, x is an integer having an average value of from 1 to 20, more preferably from 6 to 15.
As described above, when, in the preferred embodiments, and x is greater than 2, R3 may be the same or different. That is, R3 may vary between any of the alklyeneoxy units as described above. For instance, if x is 3, R3may be be selected to form ethlyeneoxy(EO) or propyleneoxy(PO) and may vary in order of (EO)(PO)(EO), (EO)(EO)(PO); (EO)(EO)(EO); (PO)(EO)(PO); (PO)(PO)(EO) and (PO)(PO)(PO). Of course, the integer three is chosen for example only and the variation may be much larger with a higher integer value for x and include, for example, mulitple (EO) units and a much small number of (PO) units.
Particularly preferred surfactants as described above include those that have a low cloud point of less than 20xc2x0 C. These low cloud point surfactants may then be employed in conjunction with a high cloud point surfactant as described in detail below for superior grease cleaning benefits.
Most preferred ether-capped poly(oxyalkylated) alcohol surfactants are those wherein k is 1 and j is 1 so that the surfactants have the formula:
R1O[CH2CH(R3)O]xCH2CH(OH)CH2OR2
where R1, R2 and R3 are defined as above and x is an integer with an average value of from 1 to 30, preferably from 1 to 20, and even more preferably from 6 to 18. Most preferred are surfactants wherein R1 and R2 range from 9 to 14, R3 is H forming ethyleneoxy and x ranges from 6 to 15.
The ether-capped poly(oxyalkylated) alcohol surfactants comprise three general components, namely a linear or branched alcohol, an alkylene oxide and an alkyl ether end cap. The alkyl ether end cap and the alcohol serve as a hydrophobic, oil-soluble portion of the molecule while the alkylene oxide group forms the hydrophilic, water-soluble portion of the molecule.
These surfactants exhibit significant improvements in spotting and filming characteristics and removal of greasy soils, when used in conjunction with high cloud point surfactants, relative to conventional surfactants.